This invention relates to hearing aids, and particularly to in-canal hearing aids including means for minimizing entry into the hearing aids of wax-fluid-like substances present within the ear canal and for solvent washing away such substances adhering to the hearing aids.
A major problem in the use of small hearing aids for full insertion within the ear canal of a user is the clogging of and even permanent damage to the hearing aid caused by penetration of foreign substances into the hearing aid. Primarily, although not limited thereto, such foreign substances are wax-like ear secretions and various fluids - both oil-like secretions and water entering the ear during washing and the like.
The prior art shows many examples of means for protecting hearing aids from such substances. One typical arrangement is shown in U.S. Pat. No. 4,984,277 to Bisgaard, et al. Therein is shown a typical in-canal hearing aid terminating in a sound port pointing, during use of the hearing aid, directly towards the user""s ear drum. For preventing entry of foreign substances into the sound port, a small cap-like, impervious shield is mounted on the hearing aid directly in front of the sound port but spaced therefrom by mounting legs. Sound exiting from the sound port passes outwardly from the hearing aid through the spaces between the shield mounting legs and, while the sound is thus not directly aimed at the ear drum, the sound is guided by the walls of the ear canal to the ear drum.
As described in the patent, a primary function of the cap-like shield is to prevent foreign substances within the ear canal from being forced directly into the hearing aid during insertion of the hearing aid into the ear canal. In effect, the cap-like shield functions as a plow for pushing aside foreign substances in the path of advance of the hearing aid.
In a number of other patents, such as U.S. Pat. Nos. 3,408,461, 4,532,649, 4,706,778 and 4,972,488, apertured plates or screens are placed over the hearing aid sound port for trapping and collecting wax which would otherwise migrate directly into the sound port. A problem in all these patents (including the aforecited Bisgaard et al patent), is that the various openings through the plates or screens (or around the Bisgaard et al cap) are pervious to fluids within the ear canal which can pass through the openings directly into the heating aid. While collected wax is likely to merely clog the sound exit, fluids entering into the hearing aid receiver are likely to permanently damage the receiver. Also, because of the possibility of entry of fluids into the receiver, the use of wax-dissolving solvents for washing away accumulated wax is generally precluded. Thus, removal of accumulated wax can be quite difficult.
While many other patents show various schemes for collecting or trapping foreign substances as a means for protecting the hearing aids, experience has shown that such collection mechanisms are generally unsatisfactory and, indeed, many presently used hearing aids effectively ignore the problem and leave to the user the need for frequent cleaning or replacement of the hearing aid. The present invention greatly improves this situation.
An in-canal hearing aid includes a receiver having a sound port facing, when in use, directly towards the ear drum. Disposed directly in front of the sound port is a foreign substance shield which serves two functions: a) it provides a gravity assisted path for fluids downwardly past the sound port and directly to the floor of the ear canal below and preferably spaced from the sound port; and b) it provides surface areas along such fluid flow paths for accumulation of waxy solids which, upon removal of the hearing aid for cleaning, can be washed away with solvents likewise safely drained past the sound port.
In a first embodiment, the shield comprises an impervious hood spaced from the sound port and completely surrounding it except for a sound exit disposed downwardly of the sound port and facing directly towards the floor of the ear canal. Optionally, the downwardly facing sound exit is covered by a screen or mesh serving, primarily, for preventing direct insertion of foreign substances residing on hairs within the ear canal into the sound exit.
In a second embodiment, the shield comprises a sound pervious hood formed from a mesh which can be pervious to fluids but which is so spaced apart from entrances into the hearing aid that fluids reaching the mesh follow gravity assisted paths along surfaces of the mesh downward past and below the hearing aid entrances.
In both embodiments, while wax can possibly accumulate on surfaces of the hood, the downward slope of the hood serves as a gravity separator of the more mobile fluid components of the foreign substances for guided flow of the fluid components downwardly past and away from the hearing aid sound port.
The inventive hoods can comprise separate, preformed members, which can be fastened, e.g., by gluing, to existing hearing aids and which can be provided as a kit of differently dimensioned hoods.
Owing to the distance of the hood sound exit from the receiver sound port, solvent washing of wax from the vicinity of the hood exit is readily done with little danger of the solvent reaching and entering the receiver sound port.